Lithography patterning technique

ABSTRACT

A lithography developing composition includes an alkaline aqueous solution having a quaternary ammonium hydroxide with both a steric functional group and an electron withdrawing group on its side chains.

PRIORITY

This is a divisional application of U.S. patent application Ser. No.15/588,773, filed May 8, 2017, which is a divisional application of U.S.patent application Ser. No. 14/529,944, filed Oct. 31, 2014, issued U.S.Pat. No. 9,645,497. Both of these applications are herein incorporatedby reference in its entirety.

BACKGROUND

The semiconductor integrated circuit (IC) industry has experiencedexponential growth. Technological advances in IC materials and designhave produced generations of ICs where each generation has smaller andmore complex circuits than the previous generation. In the course of ICevolution, functional density (i.e., the number of interconnecteddevices per chip area) has generally increased while geometry size(i.e., the smallest component (or line) that can be created using afabrication process) has decreased. This scaling down process generallyprovides benefits by increasing production efficiency and loweringassociated costs. Such scaling down has also increased the complexity ofprocessing and manufacturing ICs.

For example, lithography has been the traditional method fortransferring IC patterns to semiconductor wafers. In a typicallithography process, a resist film is coated on a surface of a wafer andis subsequently exposed and developed to form a resist pattern. Theresist pattern is then used for etching the wafer to form an IC. Thequality of the resist pattern directly impacts the quality of the finalIC. As the scaling down process continues, line edge roughness (LER) andline width roughness (LWR) of the resist pattern have become morecritical. Multiple factors affect the LER/LWR of a resist pattern, amongwhich is the chemical solution used for developing the exposed resistfilm.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is best understood from the following detaileddescription when read with the accompanying figures. It is emphasizedthat, in accordance with the standard practice in the industry, variousfeatures are not drawn to scale and are used for illustration purposesonly. In fact, the dimensions of the various features may be arbitrarilyincreased or reduced for clarity of discussion.

FIG. 1 illustrates a flow chart of a lithography patterning methodaccording to various aspects of the present disclosure.

FIGS. 2A, 2B, 2C, and 2D illustrate cross sectional views of forming atarget pattern according to the method of FIG. 1 , in accordance with anembodiment.

FIGS. 3A and 3B illustrate edge roughness, width roughness, and criticaldimension of a resist pattern.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

The present disclosure is generally related to methods for semiconductordevice fabrication, and more particularly to methods of lithographypatterning. In lithography patterning, after a resist film is exposed,it is developed in a developer (a chemical solution). The developerremoves portions of the resist film, thereby forming a resist patternwhich may include line patterns and/or trench patterns. The resistpattern is used as an etch mask in subsequent etching processes,transferring the pattern to underlying patterning layers. The linesand/or trenches of a resist pattern usually have non-uniform side walldimensions (e.g., LER or LWR) due to various factors, some of which arerelated to the properties of the developer. For example, the developermay penetrate the resist film with varying depth at different areas ofthe resist film. Some developer molecules may even stay inside theresist patterns after the developing process and cause portions of theresist patterns to swell. Such dimension non-uniformity in a resistpattern may contribute to degradation of IC performance and should beavoided whenever possible. This is particularly true in nanometer (nm)fabrication regimes. The present disclosure provides methods andcompositions for developing resist films so as to improve dimensionuniformity of resist patterns.

FIG. 1 is a flow chart of a method 100 of patterning a substrate (e.g.,a semiconductor wafer) according to various aspects of the presentdisclosure. The method 100 may be implemented, in whole or in part, by asystem employing deep ultraviolet (DUV) lithography, extreme ultraviolet(EUV) lithography, electron beam (e-beam) lithography, x-raylithography, and other lithography processes to improve patterndimension accuracy. Additional operations can be provided before,during, and after the method 100, and some operations described can bereplaced, eliminated, or moved around for additional embodiments of themethod. The method 100 is an example, and is not intended to limit thepresent disclosure beyond what is explicitly recited in the claims. Themethod 100 is described below in conjunction with FIGS. 2A-2D wherein asemiconductor device 200 is fabricated by using embodiments of themethod 100. The semiconductor device 200 may be an intermediate devicefabricated during processing of an IC, or a portion thereof, that maycomprise SRAM and/or other logic circuits, passive components such asresistors, capacitors, and inductors, and active components such asp-type FETs (PFETs), n-type FETs (NFETs), fin-like FETs (FinFETs), otherthree-dimensional (3D) FETs, metal-oxide semiconductor field effecttransistors (MOSFET), complementary metal-oxide semiconductor (CMOS)transistors, bipolar transistors, high voltage transistors, highfrequency transistors, other memory cells, and combinations thereof.

The method 100 (FIG. 1 ) is provided with a substrate 202 (FIG. 2A) atoperation 102. Referring to FIG. 2A, the substrate 202 includes one ormore layers of material or composition. In an embodiment, the substrate202 is a semiconductor substrate (e.g., wafer). In another embodiment,the substrate 202 includes silicon in a crystalline structure. Inalternative embodiments, the substrate 202 includes other elementarysemiconductors such as germanium, or a compound semiconductor such assilicon carbide, gallium arsenide, indium arsenide, and indiumphosphide. The substrate 202 may include a silicon on insulator (SOI)substrate, be strained/stressed for performance enhancement, includeepitaxial regions, include isolation regions, include doped regions,include one or more semiconductor devices or portions thereof, includeconductive and/or non-conductive layers, and/or include other suitablefeatures and layers. In the present embodiment, the substrate 202includes a patterning layer 204. In an embodiment, the patterning layer204 is a hard mask layer including material(s) such as amorphous silicon(a-Si), silicon oxide, silicon nitride (SiN), titanium nitride, or othersuitable material or composition. In an embodiment, the patterning layer204 is an anti-reflection coating (ARC) layer such as a nitrogen-freeanti-reflection coating (NFARC) layer including material(s) such assilicon oxide, silicon oxygen carbide, or plasma enhanced chemical vapordeposited silicon oxide. In various embodiments, the patterning layer204 may include a high-k dielectric layer, a gate layer, a hard masklayer, an interfacial layer, a capping layer, a diffusion/barrier layer,a dielectric layer, a conductive layer, other suitable layers, and/orcombinations thereof. In another embodiment, the substrate 202 is a masksubstrate that may include a low thermal expansion material such asquartz, silicon, silicon carbide, or silicon oxide-titanium oxidecompound. To further this example, the substrate 202 may be a masksubstrate for making a deep ultraviolet (DUV) mask, an extremeultraviolet (EUV) mask, or other types of masks.

The method 100 (FIG. 1 ) proceeds to operations 104 by forming amaterial layer 206 over the substrate 202 (FIG. 2B). Referring to FIG.2B, in an embodiment, the material layer 206 is formed by spin-oncoating a liquid polymeric material onto the substrate 202, followed bya soft baking process and a hard baking process. In an embodiment, thematerial layer 206 is a radiation sensitive layer, such as a photoresistincluding an I-line resist, a DUV resist including a krypton fluoride(KrF) resist and argon fluoride (ArF) resist, a EUV resist, an electronbeam (e-beam) resist, and an ion beam resist. For the sake ofconvenience, the material layer 206 is simply referred to as the resist206 in the following discussion. In various embodiments, the resist 206contains both acid labile groups (ALGs) and non-ALGs. Exemplary non-ALGsinclude lactone, alcohol, ketone, and some polar units. One materialsuitable for the resist 206 is a chemically amplified resist (CAR) thatcontains backbone polymer protected by ALGs. The CAR further containsphoto-acid generators (PAGs) which, upon radiation, produce an acid. Theacid can catalyze the cleaving of the ALGs from the backbone polymer,though often requiring that the resist-coated substrate 202 be heated(such as in a post exposure baking (PEB) process). This cleavingreaction is catalytic, in the sense that the acid still remains afterthe reaction, and is therefore available to promote the cleaving ofadditional ALGs. Such a cleaving reaction will be terminated only whenthe acid produced comes in contact with a base, also referred to as abase quencher. When the ALGs leave the backbone polymer, the branch unitof the polymer will be changed to carboxylic group that increases thepolymer's solubility to a positive tone developer; thus, allowing theirradiated area of the resist to be removed by the developer, while thenon-irradiated area remains insoluble and becomes a masking element forsubsequent processes. This type of resist is referred to as a positiveresist. Another type of resist, a negative resist, has the oppositebehavior: it is generally soluble in a developer, but becomes insolubleupon radiation. In the present embodiment, the resist 206 is a positiveresist.

The method 100 (FIG. 1 ) proceeds to operation 106 by exposing theresist 206 to a radiation 208 in a lithography system. Referring to FIG.2B, the radiation 208 may be an I-line (365 nm), a DUV radiation such asKrF excimer laser (248 nm) or ArF excimer laser (193 nm), a EUVradiation (e.g., 13.8 nm), an e-beam, an x-ray, an ion beam, or othersuitable radiations. Operation 106 may be performed in air, in a liquid(immersion lithography), or in a vacuum (e.g., for EUV lithography ande-beam lithography). In an embodiment, the radiation 208 is patternedwith a mask, such as a transmissive mask or a reflective mask, which mayinclude resolution enhancement techniques such as phase-shifting and/oroptical proximity correction (OPC). In another embodiment, the radiation208 is directly modulated with a predefined pattern, such as an IClayout, without using a mask (maskless lithography). In the presentembodiment, the radiation 208 exposes portions of the resist 206according to a pattern, either with a mask or maskless. The irradiatedportions of the resist 206 become soluble in a developer. Additionally,the semiconductor device 200 may be subjected to one or morepost-exposure baking processes, which accelerate the cleaving of theALGs as discussed above.

The method 100 (FIG. 1 ) proceeds to operation 108 by developing theexposed resist 206 in a developer 210, constructed according to variousaspects of the present disclosure. Portions of the resist 206 areremoved by the developer 210, resulting a resist pattern 206 a (FIG.2C). In the example as shown in FIG. 2C, the resist pattern 206 a arerepresented by two line patterns. However, the following discussion isequally applicable to resist patterns represented by trenches.

As discussed above, the quality of the resist pattern 206 a directlyimpacts the quality of the final fabricated product(s). Among variousmeasures of the quality of the resist pattern 206 a are the surfaceuniformity of its sidewalls. Such uniformity is usually given in termsof line edge roughness (LER) and/or line width roughness (LWR). FIG. 3Aillustrates a cross-sectional view of a line pattern, showing roughnessof its sidewalls. FIG. 3B illustrates surface roughness along the linepattern in the “y” direction (or its length direction). In the presentembodiment, LER is defined as a 3σ deviation of an edge from a line fitto that edge, or mathematically, LER=∛√{square root over (Σ_(i=0)^(n)(x_(i)−x)²/n)}; and LWR is defined as a 3σ deviation of the linewidth, CD, along the line, or mathematically, LWR=∛√{square root over(Σ_(j=0) ^(n)(CD_(j)−CD)²/n)}. Such non-ideal CD and undesirable LER/LWRmay be transferred from the line pattern to a substrate, causing ICfabrication issues. For example, the line pattern may be used to patterna transistor gate electrode whose gate length corresponds to the widthof the line pattern. Gate length is a critical feature of a transistorbecause it may affect power consumption and/or switching speed of thetransistor. Undesirable LER/LWR can cause the gate length to be out ofdesign specification.

The Applicants have identified some properties of traditional developersthat might have caused excessive LER and LWR in existing resistdevelopment processes, which will be explained below. In some respects,resist development can be analogized as individual developer moleculesetching (dissolving) the resist material surrounding them. Developerswith stronger basicity exhibit larger etching distance, i.e. more resistmaterial being dissolved by each developer molecule. This, combined withrandom molecular penetration depth inside the resist surface, createsuneven resist sidewalls. Some developers have greater penetrationstrength, creating more randomness in the etching depth. Some developermolecules even stay inside the resist pattern after the development andsubsequently cause swelling of the resist pattern. All of thesephenomena lead to excessive LER and LWR in the developed resistpatterns.

The present disclosure addresses the above problems with innovativedeveloper solutions. Lab experiments have shown that the resist pattern206 a developed with embodiments of the present disclosure shows reducedLER and LWR compared with resist patterns developed with traditionaldevelopers. This is very desirable for advanced process nodes, such as10 nanometer (nm) and beyond.

In an embodiment, the developer 210 is an alkaline aqueous solutionhaving an organic base that is a quaternary ammonium hydroxide. In anembodiment, the quaternary amine has one or more bulky groups in itsside chains. The one or more bulky groups have steric functions thatreduce the developer 210's penetration strength. This provides one ormore benefits for the developing of the resist pattern 206 a. Forexample, the molecules of the organic base in the developer 210 tend tostay close to the surface of the resist 206, reducing etching depthrandomness. The number of developer molecules inside the developedresist pattern 206 a is also reduced, reducing the swelling thereof. Thenet effect is that, with the developer 210, the resist pattern 206 aattains smoother sidewalls.

In an embodiment, the organic base in the developer 210 is representedby the formula (Formula (1)):

wherein R₁—Z₁, R₂—Z₂, R₃—Z₃, and R₄—Z₄ are steric functional groups.

In various embodiments, R₁, R₂, R₃, and/or R₄ include an unbranchedgroup, a branched group, a cyclic group, a noncyclic group, a saturatedgroup, an unsaturated group, an alkyl chain, or an aromatic ring.Furthermore, R₁, R₂, R₃, and/or R₄ may have a chain carbon numberbetween about 1 and about 15. In the present example, at least one ofR₁—Z₁, R₂—Z₂, R₃—Z₃, and R₄—Z₄ has a van der Waals volume larger than anethylene group. In an embodiment, at least one of R₁, R₂, R₃, and R₄ hasa formula (R₅O)_(n)H wherein R₅ is an alkylene of 1 to 3 carbons and nis an integer ranging from 1 to 20.

Z₁, Z₂, Z₃, and/or Z₄ comprise a pendant group. The pendant group may beselected from the group consisting of —H, —Cl, —Br, —I, —NO₂, —SO₃—,—H—, —CN, —NCO, —OCN, —CO₂—, —OH, —OR*, —OC(O)CR*, —SR, —SO₂N(R*)₂,—SO₂R*, SOR, —C(O)R*, —C(O)OR*, —Si(OR*)₃, —Si(R*)₃, and an epoxylgroup. In the above formulae, R* includes at least one of hydrogen, anunbranched group, a branched group, a cyclic group, a noncyclic group, asaturated group, an unsaturated group, an alkyl group, an alkenyl group,and an alkynyl group.

In one example, the organic base of the developer 210 isTetrabutylammonium hydroxide (TBAH). In another example, the organicbase of the developer 210 is Tetrapropylammonium hydroxide (TPAH).

In another embodiment, the developer 210 is an alkaline aqueous solutionwith low alkaline concentration (or loading). As discussed above, thestronger basicity of a developer, the greater etching distance of itsmolecules. Therefore, reducing basicity of a developer will lead tosmaller LER and LWR of a developed resist pattern. In an embodiment, thedeveloper 210 is an alkaline aqueous solution with an alkalineconcentration in the range of about 0.01% to about 2%, such as fromabout 0.5% to about 2%. In an embodiment, the developer 210 includes afirst concentration of an organic base that is a quaternary ammoniumhydroxide wherein the first concentration is in the range of about 0.01%to about 2.37%, such as from about 0.5% to about 2%, and the quaternaryammonium hydroxide has one or more bulky groups in its side chains asdiscussed above. In this embodiment, the developer 210 has the combinedproperty of low penetration strength and low basicity, and therefore canbe used for producing resist patterns with low LER and LWR. In oneexample of such an embodiment, the concentration of the organic base inthe developer 210 is less than 1.5%.

In yet another embodiment, the developer 210 is an alkaline aqueoussolution having an organic base that is a quaternary ammonium hydroxidewith weak basicity. In one example, the quaternary ammonium hydroxidehas basicity weaker than Tetramethylammonium hydroxide (TMAH). Inanother example, the pka of the quaternary ammonium hydroxide is lessthan 9.8. In an embodiment, this quaternary ammonium hydroxide can berepresented by the following formula (Formula (2)):

R₅, R₆, R₇, and R₈ are each selected from a group consisting of a singlebond, an unbranched group, a branched group, a cyclic group, a noncyclicgroup, a saturated group, an unsaturated group, an alkyl chain, and anaromatic ring.

L₅, L₆, L₇, and/or L₅ comprise an electron withdrawing group thatdecreases the basicity of the quaternary ammonium hydroxide. Theelectron withdrawing group may be selected from the group consisting of—F, —Cl, —Br, —I, —BF₃, —CF₃, —CN, C═O, C═C, CHO, NO₂, —COR, COOR, COOH,CONHR, BR₂, SO₃R, —NHCOR, -phenyl, -pyridine, —SOR, -alkyl, —SO₂F,diketone, naphthalene, diphenyl, fluorine, and indene.

In an embodiment, the developer 210 is an alkaline aqueous solution thatincludes a first organic base and a second organic base, wherein thefirst organic base is represented by Formula (1) above and the secondorganic base is represented by Formula (2) above. The developer 210 mayfurther have a low organic base concentration in the range of about0.01% to about 2%.

In yet another embodiment, the developer 210 is an alkaline aqueoussolution that includes an organic base having properties equivalent tothe ones represented by both Formula (1) and Formula (2). In oneexample, the organic base is represented by the following formula(Formula (3)):

One chemical represented by Formula (3) isBenzyldimethyltetradecylammonium hydroxide. In another example, theorganic base is represented by the following formula (Formula (4)):

One chemical represented by Formula (4) is Trimethylphenylammoniumhydroxide. In this embodiment, the developer 210 may further have a loworganic base concentration in the range of about 0.01% to about 2%, suchas from about 0.5% to about 1.5%. The developer 210 thus has thecombined property of low penetration strength, low basicity, and lowloading effect. It therefore can be used to develop the resist pattern206 a with extremely low LER and LWR, ideal for nanometer ICfabrication.

In various embodiments discussed above, the developer 210 may furtherinclude a surfactant. The surfactant improves the developer 210'swettability to the bottom of trench patterns, reduces its capillaryforce, and reduces bubbling during resist development.

Still referring to FIG. 2C, the developer 210, constructed according tovarious aspects of the present disclosure, is applied to the resist 206.The exposed portions of the resist 206 are dissolved by the developer210, leaving the unexposed portion 206 a as the resist pattern over thesubstrate 202. Due to the properties of the developer 210 discussedabove, the resist pattern 206 a has very low LER and LWR. In variousembodiments, the developer 210 can be continuously sprayed onto thesemiconductor device 200, or can be applied by other means such as apuddle process. The method 100 may include further operations tofinalize the resist pattern 206 a after operation 108. For example, thesemiconductor device 200 may be subjected to a rinsing operation usingde-ionized (DI) water to remove residues and particles, and/or apost-development baking (PDB) process to harden the resist pattern 206 aso as to increase its structural stability.

The method 100 (FIG. 1 ) proceeds to operation 110 to etch the substrate202 using the resist pattern 206 a as an etch mask, thereby transferringthe pattern from the resist pattern 206 a to the substrate 202 (FIG.2D). In an embodiment, the patterning layer 204 is a hard mask layer. Tofurther this embodiment, the pattern is first transferred from theresist pattern 206 a to the hard mask layer 204, then to other layers ofthe substrate 202. For example, the hard mask layer 204 may be etchedthrough openings of the resist pattern 206 a using a dry (plasma)etching, a wet etching, and/or other etching methods. For example, a dryetching process may implement an oxygen-containing gas, afluorine-containing gas (e.g., CF₄, SF₆, CH₂F₂, CHF₃, and/or C₂F₆), achlorine-containing gas (e.g., Cl₂, CHCl₃, CCl₄, and/or BCl₃), abromine-containing gas (e.g., HBr and/or CHBR₃), an iodine-containinggas, other suitable gases and/or plasmas, and/or combinations thereof.The resist pattern 206 a may be partially or completely consumed duringthe etching of the hard mask layer 204. In an embodiment, any remainingportion of the resist pattern 206 a may be stripped off, leaving apatterned hard mask layer 204 a over the substrate 202, as illustratedin FIG. 2D.

Although not shown in FIG. 1 , the method 100 may proceed to forming afinal pattern or an IC device on the substrate 202. In an embodiment,the substrate 202 is a semiconductor substrate and the method 100proceeds to forming fin field effect transistor (FinFET) structures. Inthis embodiment, operation 110 forms a plurality of active fins in thesemiconductor substrate 202. The active fins have uniform CD, thanks tothe extreme low LER and LWR of the resist pattern 206 a. In anotherembodiment, the method 100 proceeds to forming a plurality of gateelectrodes in the semiconductor substrate 202. The gate electrodes haveuniform gate length due to the resist pattern 206 a's smooth sidewalls.The method 100 may further form gate spacers, doped source/drainregions, contacts for gate/source/drain features, etc. In anotherembodiment, a target pattern is to be formed as metal lines in amultilayer interconnection structure. For example, the metal lines maybe formed in an inter-layer dielectric (ILD) layer of the substrate 202,which has been etched by operation 110 to include a plurality oftrenches. The method 100 proceeds to filling the trenches with aconductive material, such as a metal; and polishing the conductivematerial using a process such as chemical mechanical polishing (CMP) toexpose the patterned ILD layer, thereby forming the metal lines in theILD layer. The above are non-limiting examples of devices/structuresthat can be made and/or improved using the method 100 and the developer210 according to various aspects of the present disclosure.

Although not intended to be limiting, one or more embodiments of thepresent disclosure provide many benefits to a semiconductor device andthe formation thereof. For example, a resist developer constructedaccording to the present disclosure provides low basicity, low molecularpenetration, and/or low etching distance. Using such resist developerleads to reduced resist penetration depth randomness, reduced resistpattern swelling, and reduced resist pattern surface roughness such asline edge roughness (LER) and/or line width roughness (LWR). Such resistdeveloper is advantageous in nanometer semiconductor fabrication wherecritical dimension (CD) uniformity has become a critical factor inensuring circuit performance.

In one exemplary aspect, the present disclosure is directed to a methodfor lithography patterning. The method includes providing a substrate;forming a material layer over the substrate; exposing the material layerto a radiation, resulting in an exposed material layer; and removing aportion of the exposed material layer in a developer, resulting in apatterned material layer. The developer is an alkaline aqueous solutionhaving an organic base that is a quaternary ammonium hydroxide.

In another exemplary aspect, the present disclosure is directed to amethod for lithography patterning. The method includes forming amaterial layer over a substrate; exposing the material layer to aradiation, resulting in an exposed material layer; and removing aportion of the exposed material layer in a developer, resulting in apatterned material layer. The developer is an alkaline aqueous solutionhaving an organic base and the developer has basicity weaker thanTetramethylammonium hydroxide (TMAH).

In another exemplary aspect, the present disclosure is directed to alithography developing composition. The composition includes an aqueoussolvent and an organic base that is represented by the formula:

wherein R₁—Z₁, R₂—Z₂, R₃—Z₃, and R₄—Z₄ are steric functional groups, Z₁,Z₂, Z₃, and Z₄ are each a pendant group, and at least one of R₁—Z₁,R₂—Z₂, R₃—Z₃, and R₄—Z₄ has a van der Waals volume greater than anethylene group.

In an exemplary aspect, the present disclosure is directed to alithography developing composition. The composition includes an alkalineaqueous solution having a first organic base and a second organic base,wherein the first organic base is a quaternary ammonium hydroxide withpendant groups on its side chains and the second organic base is anotherquaternary ammonium hydroxide with electron withdrawing groups on itsside chains.

In another exemplary aspect, the present disclosure is directed to alithography developing composition. The composition includes an alkalineaqueous solution having an organic base that is a quaternary ammoniumhydroxide with at least one electron withdrawing group on its sidechains and the organic base has basicity weaker than Tetramethylammoniumhydroxide (TMAH).

In yet another exemplary aspect, the present disclosure is directed to alithography developing composition. The composition includes an alkalineaqueous solution having an organic base that is Trimethylphenylammoniumhydroxide or Benzyldimethyltetradecylammonium hydroxide.

The foregoing outlines features of several embodiments so that those ofordinary skill in the art may better understand the aspects of thepresent disclosure. Those of ordinary skill in the art should appreciatethat they may readily use the present disclosure as a basis fordesigning or modifying other processes and structures for carrying outthe same purposes and/or achieving the same advantages of theembodiments introduced herein. Those of ordinary skill in the art shouldalso realize that such equivalent constructions do not depart from thespirit and scope of the present disclosure, and that they may makevarious changes, substitutions, and alterations herein without departingfrom the spirit and scope of the present disclosure.

What is claimed is:
 1. A lithography developing composition, comprisingan alkaline aqueous solution having a quaternary ammonium hydroxide withboth a steric functional group and an electron withdrawing group on itsside chains, wherein the quaternary ammonium hydroxide is represented bya formula:

wherein at least one of the R₁—Z₁, R₂—Z₂, R₃—Z₃, and R₄—Z₄ is the stericfunctional group, wherein at least one of R₁, R₂, R₃, and R₄ has aformula (R₅O)_(n), wherein R₅ is an alkylene of 1 to 3 carbons and n isan integer ranging from 7 to 20, and wherein at least one of the Z₁, Z₂,Z₃, and Z₄ includes a first moiety selected from the group consisting of—Cl, —Br, —I, —NO₂, —SO₃—, —CN, —NCO, —OCN, —CO₂—, —OC(O)CR*,—SO₂N(R*)₂, —SO₂R*, —C(O)R*, —C(O)OR*, —Si(OR*)₃, —Si(R*)₃, and anepoxyl group, and wherein R* is selected from at least one of hydrogen,an unbranched group, a branched group, a cyclic group, a noncyclicgroup, a saturated group, an unsaturated group, an alkyl group, analkenyl group, and an alkynyl group.
 2. The lithography developingcomposition of claim 1, wherein at least one of the R₁—Z₁, R₂—Z₂, R₃—Z₃,and R₄—Z₄ is the electron withdrawing group.
 3. The lithographydeveloping composition of claim 1, wherein the steric functional grouphas a van der Waals volume greater than an ethylene group.
 4. Thelithography developing composition of claim 1, wherein the electronwithdrawing group includes a second moiety selected from the groupconsisting of —BF₃, —CF₃, C═O, C═C, CHO, NO₂, COOH, -pyridine, —SO₂F,diketone, naphthalene, diphenyl, fluorine, and indene.
 5. Thelithography developing composition of claim 1, wherein the quaternaryammonium hydroxide has a concentration in the alkaline aqueous solutionranging from 0.01% to 2%.
 6. The lithography developing composition ofclaim 1, wherein the quaternary ammonium hydroxide has a pKa less than9.8.
 7. A lithography developing composition, comprising an alkalineaqueous solution having a quaternary ammonium hydroxide with at leastone electron withdrawing group on its side chains and the quaternaryammonium hydroxide has a basicity weaker than Tetramethylammoniumhydroxide (TMAH), wherein the electron withdrawing group includes afirst moiety selected from the group consisting of —BF₃, —CF₃, C═O, C═C,CHO, NO₂, COOH, -pyridine, —SO₂F, diketone, naphthalene, diphenyl,fluorine, and indene, wherein the quaternary ammonium hydroxide isrepresented by a formula:

wherein R₁, R₂, R₃, and R₄ are each selected from a group consisting of:an unbranched group, a branched group, a cyclic group, a noncyclicgroup, a saturated group, an unsaturated group, an alkyl chain, and anaromatic ring, wherein at least one of the R₁—Z₁, R₂—Z₂, R₃—Z₃, andR₄—Z₄ is a steric functional group, wherein in the steric functionalgroup, R₁, R₂, R₃, or R₄ has a chain carbon number between 7 and 15, andZ₁, Z₂, Z₃, or Z₄ includes a second moiety selected from the groupconsisting of —Cl, —Br, —I, —NO₂, —SO₃—, —CN, —NCO, —OCN, —CO₂—,—OC(O)CR*, —SO₂N(R*)₂, —SO₂R*, —C(O)R*, —C(O)OR*, —Si(OR*)₃, —Si(R*)₃,and an epoxyl group, wherein R* is selected from at least one ofhydrogen, an unbranched group, a branched group, a cyclic group, anoncyclic group, a saturated group, an unsaturated group, an alkylgroup, an alkenyl group, and an alkynyl group.
 8. The lithographydeveloping composition of claim 7, wherein the steric functional grouphas a van der Waals volume greater than an ethylene group.
 9. Thelithography developing composition of claim 7, wherein at least one ofthe R₁—Z₁, R₂—Z₂, R₃—Z₃, and R₄—Z₄ is the electron withdrawing group;and the quaternary ammonium hydroxide has a pKa less than 9.8.
 10. Thelithography developing composition of claim 9, wherein in the electronwithdrawing group, Z₁, Z₂, Z₃, or Z₄ includes the first moiety.
 11. Thelithography developing composition of claim 7, wherein the quaternaryammonium hydroxide includes a third moiety (R₅O)_(n) on its side chains,wherein R₅ is an alkylene of 1 to 3 carbons and n is an integer rangingfrom 7 to
 20. 12. The lithography developing composition of claim 7,wherein a concentration of the quaternary ammonium hydroxide in thealkaline aqueous solution ranges from 0.01% to 2%.
 13. The lithographydeveloping composition of claim 7, wherein the at least one electronwithdrawing group is selected to reduce the basicity of the alkalineaqueous solution.
 14. A lithography developing composition, comprisingan aqueous solution having a quaternary ammonium hydroxide with at leastone steric functional group and at least one electron withdrawing groupon its side chains, the steric functional group having a van der Waalsvolume greater than an ethylene group, wherein the steric functionalgroup includes a first moiety selected from the group consisting of —Cl,—Br, —I, —NO₂, —SO₃—, —CN, —NCO, —OCN, —CO₂—, —OC(O)CR*, —SO₂N(R*)₂,—SO₂R*, —C(O)R*, —C(O)OR*, —Si(OR*)₃, —Si(R*)₃, and an epoxyl group,wherein R* is selected from at least one of hydrogen, an unbranchedgroup, a branched group, a cyclic group, a noncyclic group, a saturatedgroup, an unsaturated group, an alkyl group, an alkenyl group, and analkynyl group, and wherein the steric functional group includes a thirdmoiety (R₅O)_(n), wherein R₅ is an alkylene of 1 to 3 carbons and n isan integer ranging from 7 to
 20. 15. The lithography developingcomposition of claim 14, wherein the quaternary ammonium hydroxide isdissolved in an aqueous solution at a concentration ranging from 0.01%to 2%, has a basicity weaker than that of tetramethylammonium hydroxide(TMAH).
 16. The lithography developing composition of claim 1, whereinR₁, R₂, R₃, or R₄ are each selected from the group consisting of anunbranched group, a branched group, a cyclic group, a noncyclic group, asaturated group, an unsaturated group, an alkyl chain, and an aromaticring.
 17. The lithography developing composition of claim 11, whereinthe steric functional group includes the third moiety (R₅O)_(n).
 18. Thelithography developing composition of claim 14, wherein the stericfunctional group further includes a second moiety selected from thegroup consisting of an unbranched group, a branched group, a cyclicgroup, a noncyclic group, a saturated group, an unsaturated group, analkyl chain, and an aromatic ring.
 19. The lithography developingcomposition of claim 14, wherein the electron withdrawing group includesa third moiety selected from the group consisting of —BF₃, —CF₃, C═O,C═C, CHO, NO₂, COOH, -pyridine, —SO₂F, diketone, naphthalene, diphenyl,fluorine, and indene.
 20. The lithography developing composition ofclaim 1, wherein at least one of R₁, R₂, R₃, and R₄ have a chain carbonnumber between 7 and 15.